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H.264 is Magic

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Re: H.264 is Magic

#91

Post by erydo »

amluto wrote: post #65

Nice article! The motion compensation bit could be improved, though: > The only thing moving really is the ball. What if you could just have one static image of everything on the background, and then one moving image of just the ball. Wouldn't that save a lot of space? You see where I am going with this? Get it? See where I am going? Motion estimation? Reusing the background isn't motion compensation -- you get that…

Your example seems to assume translation only. I wonder how difficult/useful it would be to identify other kinds of time-varying characteristics (translation, rotation, scale, hue, saturation, brightness, etc) of partial scene elements in an automated way.

Along the same lines, it would be interesting to figure out an automated time-varying-feature detection algorithm to determine which kinds of transforms are the right ones to encode.

Do video encoders already do something like this? It seems like a pretty difficult problem since there are so many permutations of applicable transformations.

Re: H.264 is Magic

#92

Post by exprA »

algesten wrote: post #44

"See how the compressed one does not show the holes in the speaker grills in the MacBook Pro? If you don't zoom in, you would even notice the difference. " Ehm, what?! The image on the right looks really bad and the missing holes was the first thing I noticed. No zooming needed. And that's exactly my problem with the majority of online video (iTunes store, Netflix, HBO etc). Even when it's called "HD", there are comp…

There's another false claim like that a bit below. I can only assume that the author is close to legally blind, or uses a VGA-res display to watch the page.

Re: H.264 is Magic

#93

Post by chrisseaton »

lostgame wrote: post #75

Absolutely love this: 'Suppose you have some strange coin - you've tossed it 10 times, and every time it lands on heads. How would you describe this information to someone? You wouldn't say HHHHHHHHH. You would just say "10 tosses, all heads" - bam! You've just compressed some data! Easy. I saved you hours of mindfuck lectures.' This is a really great, simple way to explain what is otherwise a fairly complex concept…

That's only one half of the problem - you now have an alphabet five times the size so you have actually increased the size of the message! You also need to explain how to encode this efficiently to explain compression.

Re: H.264 is Magic

#94

Post by agumonkey »

lostgame wrote: post #75

Absolutely love this: 'Suppose you have some strange coin - you've tossed it 10 times, and every time it lands on heads. How would you describe this information to someone? You wouldn't say HHHHHHHHH. You would just say "10 tosses, all heads" - bam! You've just compressed some data! Easy. I saved you hours of mindfuck lectures.' This is a really great, simple way to explain what is otherwise a fairly complex concept…

RLE a given. It's true that the average person rarely understand that this is what computers call compression, but everything after that involves a bit of thinking. Optimal huffman.

Re: H.264 is Magic

#95

Post by ComodoHacker »

alexandrerond wrote: post #39

Very well explained. But I could have understood it all without the bro-approach to the reader. You see where I am going with this? Get it? See where I am going? Ok!

Today you need tricks like that to get Twitter-generation people to read even half of that amount of text.

Re: H.264 is Magic

#96

Post by coryfklein »

algesten wrote: post #44

"See how the compressed one does not show the holes in the speaker grills in the MacBook Pro? If you don't zoom in, you would even notice the difference. " Ehm, what?! The image on the right looks really bad and the missing holes was the first thing I noticed. No zooming needed. And that's exactly my problem with the majority of online video (iTunes store, Netflix, HBO etc). Even when it's called "HD", there are comp…

Of course while reading the article you are going to be very conscious of detail and image quality because that is the subject matter of the post.

However if that MacBook Pro image was placed on the side of an article where the primary content was the text you were reading, you'd glance at the image and your brain would fill in the details for you. You probably wouldn't notice the difference in that context.

For most use cases, there likely is very little functional difference between the two images. At least, that was how I understood it.

Re: H.264 is Magic

#97

Post by _puk »

ksec wrote: post #33
iplaw wrote: post #26

H.265 gets you twice the resolution for the same bandwidth, or the same resolution for half the bandwidth.

H.265 gets you half the file size for ten times more in royalty fees, or saving 50% of bandwidth for 1000% more in royalty.

Do you have a reference for that?

I was under the impression that the first 100,000 units are free, and then 20c per unit afterwards to a max of $25m.

H264 drops to 10c per unit after 5m units, to a max of $6.5m.

You need to be shipping 125 million units annually to hit the full $25m.

Yes it's more, but it's not quite ten times. And notably if the chip maker pays the royalties, then the content creators don't need to (though that was excepted indefinitely with H264).

Parts regurgitated from a quick google for reference [1]

[1] http://www.theregister.co.uk/2014/10/03/hevc_patent_terms_th...

Re: H.264 is Magic

#98

Post by agumonkey »

adilparvez wrote: post #31

Related, how h265 works: http://forum.doom9.org/showthread.php?t=167081 This is a great overview and the techniques are similar to those of h264. I found it invaluable to get up to speed when I had to do some work on the screen content coding extensions of hevc in Argon Streams. They are a set of bit streams to verify hevc and vp9, take a look, it is a very innovative technique: http://www.argondesign.com/products/ar…

Heh, happy to see doom9 still alive and kicking. They were the n°1 resource in the early days of mainstream video compression.

Re: H.264 is Magic

#99

Post by nightcracker »

agumonkey wrote: post #94
lostgame wrote: post #75

Absolutely love this: 'Suppose you have some strange coin - you've tossed it 10 times, and every time it lands on heads. How would you describe this information to someone? You wouldn't say HHHHHHHHH. You would just say "10 tosses, all heads" - bam! You've just compressed some data! Easy. I saved you hours of mindfuck lectures.' This is a really great, simple way to explain what is otherwise a fairly complex concept…

RLE a given. It's true that the average person rarely understand that this is what computers call compression, but everything after that involves a bit of thinking. Optimal huffman.

IMO Huffman is conceptually more complicated (not the implementation, but the logic) than arithmetic coding.

And Huffman isn't optimal unless you are lucky, unlike arithmetic coding.

Re: H.264 is Magic

#100

Post by kbenson »

agumonkey wrote: post #94
lostgame wrote: post #75

Absolutely love this: 'Suppose you have some strange coin - you've tossed it 10 times, and every time it lands on heads. How would you describe this information to someone? You wouldn't say HHHHHHHHH. You would just say "10 tosses, all heads" - bam! You've just compressed some data! Easy. I saved you hours of mindfuck lectures.' This is a really great, simple way to explain what is otherwise a fairly complex concept…

RLE a given. It's true that the average person rarely understand that this is what computers call compression, but everything after that involves a bit of thinking. Optimal huffman.

The DEFLATE[1] algorithm is actually fairly accessible, and will give a good idea of how compression works.

1: https://en.wikipedia.org/wiki/DEFLATE

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